Catalytic processes for the conversion of synthesis gas into hydrocarbons and/or oxygenated hydrocarbons are well known in the art. The production of synthesis gas for use in these processes is generally accomplished by either steam reforming, autothermal reforming or non-catalytic partial oxidation of light hydrocarbons. These processes generally result in synthesis gas in a form which requires a considerable number of intermediate steps prior to conversion into useful products.
Steam reforming is a highly endothermic reaction which is carried out in multitubular reactors with excess steam. The product synthesis gas has a hydrogen to carbon monoxide ratio of at least 3:1, depending upon the excess steam used, which is higher than the ratio of about 2:1 generally required for subsequent conversion into, for example, methanol. For methanol production, the synthesis gas resulting from steam reforming requires further treatment by way of adjustment of the hydrogen to carbon monoxide ratio.
Partial oxidation of natural gas involving the use of a catalyst is an attractive route for producing synthesis gas for further conversion of synthetic hydrocarbon fuels such as middle distillates, methanol and other fuels and chemicals. The ideal process would operate at high temperatures above 1,000.degree. C. for thermodynamic reasons and at elevated pressure of 30 bar and higher and very high space velocities of 100,000 N1/en.
European Patent Application No. 0164864 relates to a process for the production of a gaseous mixture principally comprising carbon monoxide and hydrogen in a particulate bed reactor. A saturated hydrocarbon-and an oxygen-containing gas having a ratio of hydrocarbon to oxygen of greater than the stoichiometric ratio for complete combustion are introduced into the bed. The hydrocarbon and oxygen containing gas may be pre-mixed before being introduced into the bed through a nozzle. Alternatively the reactant gases may be allowed to mix at the point of injection to the bed.
European Patent Application No. 0335668 relates to a catalytic process where synthesis gas is produced by the reaction of light hydrocarbons, primarily methane, in a fluid bed reaction zone. The catalyst used in preparing the synthesis gas is such that the back reaction of carbon monoxide and hydrogen to form methane during the cooling step is substantially eliminated.
The catalytic partial oxidation process for complete premixing of the reactants at a temperature of about 800.degree. C. to about 1200.degree. C. without the possibility of flashback and without the chance of ignition of the mixture by hot walls of the mixer device or by entrained metal particles or oil droplets is, however, not easily fulfilled and careful design of this critical part of the reactor is needed especially for safety reasons.
It is an object of the present invention to ensure that the partial oxidation reactions are induced catalytically and occur simultaneously with endothermic reforming reactions without the possibility of flashback and without the chance of ignition of the mixture by the hot walls of the mixer device or by entrained metal particles or oil droplets.